Database System Having a Regulator That Performs Workload Regulation Based on Optimizer Estimates

1. A database system comprising: at least one processor; an optimizer executable on the at least one processor to generate resource estimates for corresponding steps of a query plan provided for a request to be executed in the database system; and a regulator executable on the at least one processor to produce progress information from monitoring execution of the request and to adjust a priority level of the request based on the progress information and based on the resource estimates provided by the optimizer, the regulator to further: compare the resource estimate for each of the steps of the query plan with the progress information; from the progress information, determine whether consumption of a resource is greater than or less than a corresponding resource estimate provided by the optimizer for a particular one of the steps, wherein adjusting the priority level of the request is based on the determining; receive rules defined for a plurality of workload groups; and based on the resource estimates and the received rules, assign the request to one of the plurality of workload groups.

2. The database system of claim 1 , wherein the resource estimates from the optimizer are selected from the group consisting of a time estimate, an estimate of usage of a processor resource, an estimate of usage of an input/output resource, and an estimate of usage of a network resource.

3. The database system of claim 2 , wherein the estimate of usage of the processor resource comprises an estimate of usage of one or more central processing units (CPUs) provided in one or more database nodes of the database system, wherein the estimate of usage of the input/output resource comprises an estimate of a number of accesses of a disk-based storage, and the estimate of usage of the network resource comprises an estimate of an amount of data to be communicated over a network between processing modules of the database system.

4. The database system of claim 1 , wherein the resource estimates from the optimizer comprise time estimates to indicate expected amounts of time for completion of corresponding steps of the query plan.

5. The database system of claim 4 , wherein the regulator is to increase the priority level in response to determining that execution of the request is behind schedule as specified by the time estimates.

6. The database system of claim 4 , wherein the regulator is to decrease the priority level in response to determining that execution of the request is ahead of schedule as specified by the time estimates.

7. The database system of claim 1 , wherein the regulator is executable to further determine whether execution of the request will meet a service level goal (SLG) based on considering the resource estimates, and to adjust the priority level of the request further based on the SLG.

8. The database system of claim 1 , wherein the optimizer is executable to: generate the query plan for the request.

9. A method executed by at least one processor in a database system, comprising: receiving a request; and regulating execution of the request in the database system using a regulator subsystem, wherein regulating execution of the request comprises: monitoring execution of the request to produce progress information; receiving, from an optimizer in the database system, resource estimates for steps of a query plan corresponding to execution of the request; adjusting a priority level of the request based on the progress information and based on the resource estimates, wherein the adjusting includes: comparing the resource estimate for each of the steps of the query plan with the progress information; from the progress information, determining whether consumption of a resource is greater than or less than a corresponding resource estimate provided by the optimizer for a particular one of the steps, wherein adjusting the priority level of the request is based on the determining; receiving rules defined for a plurality of workload groups; and based on the resource estimates and the received rules, assigning the request to one of the plurality of workload groups.

10. The method of claim 9 , wherein the resource estimates from the optimizer are selected from the group consisting of a time estimate, an estimate of usage of a processor resource, an estimate of usage of an input/output resource, and an estimate of usage of a network resource.

11. The method of claim 9 , wherein the resource estimates from the optimizer comprise a time estimate to indicate an expected amount of time for completion of the request, and wherein regulating execution of the request further comprises determining whether execution of the request is expected to meet the time estimate.

12. The method of claim 11 , wherein regulating execution of the request further comprises increasing the priority level in response to determining that execution of the request is behind schedule as specified by the time estimate.

13. The method of claim 11 , wherein regulating execution of the request further comprises decreasing the priority level in response to determining that execution of the request is ahead of schedule as specified by the time estimate.

14. The method of claim 11 , further comprising: determining, based on the resource estimates, whether or not execution of the request will meet a service level goal; and rejecting or aborting the request in response to determining that execution of the request will not meet the service level goal.

15. The method of claim 9 , wherein regulating execution of the request further comprises determining whether execution of the request will meet a service level goal (SLG) based on considering the resource estimates, and adjusting the priority level of the request further based on the SLG.

16. The method of claim 9 , further comprising: the optimizer generating the query plan for the request.

17. An article comprising at least one computer-readable storage medium containing instructions that when executed cause at least one processor in a database system to: receive a request; and regulate execution of the request in the database system using a regulator subsystem, wherein regulating execution of the request comprises: monitoring execution of the request to produce progress information; receiving, from an optimizer in the database system, resource estimates for steps of a query plan corresponding to execution of the request; adjusting a priority level of the request based on the progress information and based on the resource estimates, wherein the adjusting includes: comparing the resource estimate for each of the steps of the query plan with the progress information; from the progress information, determining whether consumption of a resource is greater than or less than a corresponding resource estimate provided by the optimizer for a particular one of the steps, wherein adjusting the priority level of the request is based on the determining; receiving rules defined for a plurality of workload groups; and based on the resource estimates and the received rules, assigning the request to one of the plurality of workload groups.

18. The article of claim 17 , wherein the resource estimates from the optimizer are selected from the group consisting of an estimate of usage of a processor resource, an estimate of usage of an input/output resource, and an estimate of usage of a network resource.

19. The article of claim 17 , wherein regulating execution of the request further comprises determining whether execution of the request will meet a service level goal (SLG), and adjusting the priority level of the request further based on the SLG.